{"title":"Impact of Vehicle Travel Characteristics on Level of Service: A Comparative Analysis of Rural and Urban Freeways","authors":"Anwaar Ahmed, Muhammad Bilal Khurshid, Samuel Labi","volume":95,"journal":"International Journal of Architectural and Environmental Engineering","pagesStart":1156,"pagesEnd":1161,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/9999727","abstract":"<p>The effect of trucks on the level of service is<br \/>\r\ndetermined by considering passenger car equivalents (PCE) of trucks.<br \/>\r\nThe current version of Highway Capacity Manual (HCM) uses a<br \/>\r\nsingle PCE value for all tucks combined. However, the composition<br \/>\r\nof truck traffic varies from location to location; therefore, a single<br \/>\r\nPCE value for all trucks may not correctly represent the impact of<br \/>\r\ntruck traffic at specific locations. Consequently, present study<br \/>\r\ndeveloped separate PCE values for single-unit and combination<br \/>\r\ntrucks to replace the single value provided in the HCM on different<br \/>\r\nfreeways. Site specific PCE values, were developed using concept of<br \/>\r\nspatial lagging headways (that is the distance between rear bumpers<br \/>\r\nof two vehicles in a traffic stream) measured from field traffic data.<br \/>\r\nThe study used data from four locations on a single urban freeway<br \/>\r\nand three different rural freeways in Indiana. Three-stage-leastsquares<br \/>\r\n(3SLS) regression techniques were used to generate models<br \/>\r\nthat predicted lagging headways for passenger cars, single unit trucks<br \/>\r\n(SUT), and combination trucks (CT). The estimated PCE values for<br \/>\r\nsingle-unit and combination truck for basic urban freeways (level<br \/>\r\nterrain) were: 1.35 and 1.60, respectively. For rural freeways the<br \/>\r\nestimated PCE values for single-unit and combination truck were:<br \/>\r\n1.30 and 1.45, respectively. As expected, traffic variables such as<br \/>\r\nvehicle flow rates and speed have significant impacts on vehicle<br \/>\r\nheadways. Study results revealed that the use of separate PCE values<br \/>\r\nfor different truck classes can have significant influence on the LOS<br \/>\r\nestimation.<\/p>\r\n","references":"[1] Highway Research Board \u201cHighway Capacity Manual: Practical\r\nApplications for Research, Department of Traffic and Operations,\r\nCommittee on Highway Capacity, United States Government Printing\r\nOffice, Washington, DC., 1950.\r\n[2] Highway Research Board, \u201cSpecial Report 87, Highway Capacity\r\nManual\u201d, National Research Council, Department of Traffic and\r\nOperations, Committee on Highway Capacity, Washington, D.C., 1965.\r\n[3] E. Linzer, R. Roess, and W. 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